The present invention relates to a device that receives an ophthalmic article for an inspection.
Conventional production methods for producing ophthalmic lenses, e.g., contact lenses and intraocular lenses, include lathe cutting methods and cast molding methods. A lathe cutting method produces an ophthalmic lens by cutting a solid substrate of a polymeric optical material to a designed shape. A cast molding method uses a molding process to produce an ophthalmic lens. Typically, a lens mold having two mold halves, i.e., a front curve mold half and a back curve mold half, is used to mold a lens from a polymerizable liquid composition. Once the lens is produced and before it is packaged, the lens is inspected for flaws and damages that may be created or included during the production process.
Typically, a finished lens is inspected before the lens is packaged for sale. The inspection process for ophthalmic lenses, especially hydrogel lenses, e.g., polyhydroxyethylmethacrylate contact lenses, is highly arduous since a typical ophthalmic lens is transparent, and therefore, it is difficult to locate the lens, let alone inspect the lens, especially when the lens is placed in a transparent liquid, such as water or saline solution. A conventional process for inspecting a hydrogel lens is a manual process that places the lens in a Petri dish and visually inspects the lens under a magnifying projection device. A human inspector must place the lens in a Petri dish under a magnifying projection device and locate the lens in the dish before the inspector can begin the visual inspection.
As for an automated machine vision inspection system, a lens is placed in a cell and then the cell is placed under a CCD camera to take a digital image of the lens. The digital image is analyzed with a microprocessor to detect defects in the lens. For example, U.S. Pat. No. 5,443,152 discloses an automated inspection system for a contact lens that uses an inspection cell. The patent teaches a disposable conical cell for transporting and inspecting a contact lens. Although the conical inspection cell is useful, the conical shape of the inspection cell highly or nonuniformly distorts the inspection light as the light passes through various sections of the cell.
There remains a need for an inspection cell that ensures predictable placement of a lens placed therein and does not highly and nonuniformly distort inspection light, thereby allowing a simple inspection system to be used to inspect the lens.